Form 1099 NEC

[Tridiver]

In 2020, as my work hours were reduced by my primary employer due to the pandemic, I supplemented my income by delivering groceries. Shipt sent me a 1099 NEC since I was considered a contractor. After entering the amount of roughly $5K, my tax refund was reduced by $1,700. Is TurboTax calculating this correctly? From my understanding 1099 NEC income should be taxed at 15.3% but this is more like 34%. 

Is anyone experiencing something similar?

Thanks.

[Opus 17]

Your net self-employment income is subject to 15% self-employment tax plus your regular federal income tax, which might be 15%, 22% or higher, plus state income tax.  The best way to reduce the burden of taxation on independent contractor jobs is to keep careful, accurate, and complete records of all your expenses, because expenses reduce your net profit or taxable income.

[Tridiver]

Thank you.